Disease & Conditions >>> Headache Articles & News
Diagnosing Cluster Headache
By: Ninan T. Mathew, M.D.
Cluster headache, the most severe of headache conditions, can be effectively treated when a proper diagnosis is made. The diagnosis matters because many of the medications used for migraine are ineffective for cluster headache. Even experienced physicians can misdiagnose cluster headache if they don't ask all the right questions. For this reason, a well-informed patient who correctly identifies the tell-tale symptoms of cluster headache can make an important contribution to his or her own care.
Migraine versus cluster
Cluster headache, unlike migraine, is much more frequent in males than females. Women who do have cluster headache often have features of migraine as well, complicating the diagnosis. While migraine can involve both sides of the head or switch from one side to the other, cluster headache is strictly unilateral (one-sided). During a headache period, or cluster period, the pain will remain on the same side and area of the head.
Also unlike migraine, cluster headache rarely runs in families. Many physicians who treat cluster headache patients have noticed common behavior and personality features. A majority of male patients are very heavy smokers--two to three packs of cigarettes a day. Some are also heavy drinkers, and most notice that alcohol will trigger an attack during a cluster period. It is not clear whether smoking is a cause of cluster headache, since quitting does not appear to have a direct benefit.
In addition to the unilateral location of the pain, the nature of the attack and the associated symptoms are important diagnostic clues for identifying cluster headache. Most commonly, the site of maximum pain is in and around the eye and the temple. Several symptoms involving the autonomic nervous system are usually present. (The autonomic nervous system controls involuntary processes such as digestion, body temperature, and circulation.) The affected eye will weep and redden, the pupil of eye becomes smaller, and the eyelid often droops. Nasal congestion on the affected side is common. The nausea and vomiting that often accompany migraine rarely occur in cluster headache.
Pattern of attacks
Although the pain of cluster headache is extreme, the attack is relatively brief, usually lasting 45 minutes to an hour. The pain comes on and disappears fairly rapidly, without the warning signs of migraine. During the cluster period, which commonly lasts two to three months, the usual frequency is one to three headaches a day. In episodic cluster headache, there is a pain-free remission lasting months or years between cluster periods. About 10% of cluster headache patients have chronic cluster headache, in which there are daily or near-daily attacks for more than a year without a remission period.
The cluster pattern of the attacks is an important diagnostic feature, but there are other patterns to cluster headache. During a cluster period, the sufferer may have an attack at a particular time of day everyday. An attack after coming home from work is common, and so are nocturnal attacks that wake the person up in the middle of the night. It is as if someone set a clock to have a headache at a particular time of the day or night. In fact, a "clock" may be involved. Taken together, these patterns suggest that the biological clock in the hypothalamus of the brain, which regulates sleep, appetite, hormone secretion, and other bodily cycles, may be triggering attacks.
People who get recurrent tension headache during periods of emotional or physical stress sometimes mistakenly believe that they have "cluster headache." The condition is in fact much less common than either migraine or tension headache and has characteristic features different from either. Cluster headache is reliably diagnosed by brief but extremely painful, one-sided headaches that occur in clusters--one or more a day for months--accompanied by autonomic symptoms such as a red, watery eye and nasal congestion.
Ninan T. Mathew, M.D.
Houston Headache Clinic